[jackson]

I'd asked to do an experiment about determining the molar mass of volatile liquid~~~
principle:use hypodermic syringe containing the known volume liquid to press into the stream jacket,then use ideal gas equation(i.e.PV=nRT).Therefore,n(no. of mole) is calculated.Finally,molar mass=massX1/n

but I have some questions:
1.when you're given a test tube containing the liquid,but when you transfer the liquid into the hypodermic syringe,the test tube also has a little liquid remaining the test tube....how do you do to transfer the remaining liquid into hypodermic syringe??

2.what might happen if the hypodermic needle were shorter than the nozzle of the gas syringe,and what effect would this have on your final results?

3.the results obtained using the alternative method is very slightly different.can you suggest why is so??

other question:how can I improve my chemistry??(would you suggest the studying method and some books which have the detailed chemistry knowledge??)

[jennielynn_1980]

I don't know about your first couple questions but in terms of improving chemistry I have a couple suggestions.

1. Check out the thread on this forum about good highschool chemistry textbooks.
2. I find Coles notes (or similar) really helpful for review of simple topics
3. Read the posts here

Good luck

[enahs]

Syringes, as well as all other equipment designed to deliver liquids in a chemistry labs have been properly calibrated, as such that the residual sample left over does not matter.

In other words, if it is designed to deliver exactly 0.1 milliliter, it has been calibrated to hold slightly more then 0.1 milliliter, so that what you deliver is exactly 0.1 milliliter and the excess remaining in the syringe is by design (assuming it is not really old, damaged, and you are using it at/around the temperature it has been calibrated for).

As for the test tube, the liquid left in the test tube is not important. It is just a container, the numbers you should be using to calculate with is the volume the syringe delivered to your measuring instrument, not the amount that was in the test tube.

[jackson]

1.what might happen if the hypodermic needle were shorter than the nozzle of the gas syringe,and what effect would this have on your final results?

2.the results obtained using the alternative method is very slightly different.can you suggest why is so??

[jackson]

could anyone answer these questions?? (please~~)